From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f53.google.com (mail-pa0-f53.google.com [209.85.220.53]) by kanga.kvack.org (Postfix) with ESMTP id 2CEE56B0283 for ; Tue, 5 Apr 2016 16:52:52 -0400 (EDT) Received: by mail-pa0-f53.google.com with SMTP id fe3so17772476pab.1 for ; Tue, 05 Apr 2016 13:52:52 -0700 (PDT) Received: from mail-pa0-x230.google.com (mail-pa0-x230.google.com. [2607:f8b0:400e:c03::230]) by mx.google.com with ESMTPS id a22si15774978pfj.116.2016.04.05.13.52.51 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 05 Apr 2016 13:52:51 -0700 (PDT) Received: by mail-pa0-x230.google.com with SMTP id fe3so17772332pab.1 for ; Tue, 05 Apr 2016 13:52:51 -0700 (PDT) Date: Tue, 5 Apr 2016 13:52:48 -0700 (PDT) From: Hugh Dickins Subject: [PATCH 08/10] huge pagecache: extend mremap pmd rmap lockout to files In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: "Kirill A. Shutemov" , Andrea Arcangeli , Andres Lagar-Cavilla , Yang Shi , Ning Qu , linux-kernel@vger.kernel.org, linux-mm@kvack.org Whatever huge pagecache implementation we go with, file rmap locking must be added to anon rmap locking, when mremap's move_page_tables() finds a pmd_trans_huge pmd entry: a simple change, let's do it now. Factor out take_rmap_locks() and drop_rmap_locks() to handle the locking for make move_ptes() and move_page_tables(), and delete the VM_BUG_ON_VMA which rejected vm_file and required anon_vma. Signed-off-by: Hugh Dickins --- mm/mremap.c | 42 ++++++++++++++++++++++-------------------- 1 file changed, 22 insertions(+), 20 deletions(-) --- a/mm/mremap.c +++ b/mm/mremap.c @@ -70,6 +70,22 @@ static pmd_t *alloc_new_pmd(struct mm_st return pmd; } +static void take_rmap_locks(struct vm_area_struct *vma) +{ + if (vma->vm_file) + i_mmap_lock_write(vma->vm_file->f_mapping); + if (vma->anon_vma) + anon_vma_lock_write(vma->anon_vma); +} + +static void drop_rmap_locks(struct vm_area_struct *vma) +{ + if (vma->anon_vma) + anon_vma_unlock_write(vma->anon_vma); + if (vma->vm_file) + i_mmap_unlock_write(vma->vm_file->f_mapping); +} + static pte_t move_soft_dirty_pte(pte_t pte) { /* @@ -90,8 +106,6 @@ static void move_ptes(struct vm_area_str struct vm_area_struct *new_vma, pmd_t *new_pmd, unsigned long new_addr, bool need_rmap_locks) { - struct address_space *mapping = NULL; - struct anon_vma *anon_vma = NULL; struct mm_struct *mm = vma->vm_mm; pte_t *old_pte, *new_pte, pte; spinlock_t *old_ptl, *new_ptl; @@ -114,16 +128,8 @@ static void move_ptes(struct vm_area_str * serialize access to individual ptes, but only rmap traversal * order guarantees that we won't miss both the old and new ptes). */ - if (need_rmap_locks) { - if (vma->vm_file) { - mapping = vma->vm_file->f_mapping; - i_mmap_lock_write(mapping); - } - if (vma->anon_vma) { - anon_vma = vma->anon_vma; - anon_vma_lock_write(anon_vma); - } - } + if (need_rmap_locks) + take_rmap_locks(vma); /* * We don't have to worry about the ordering of src and dst @@ -151,10 +157,8 @@ static void move_ptes(struct vm_area_str spin_unlock(new_ptl); pte_unmap(new_pte - 1); pte_unmap_unlock(old_pte - 1, old_ptl); - if (anon_vma) - anon_vma_unlock_write(anon_vma); - if (mapping) - i_mmap_unlock_write(mapping); + if (need_rmap_locks) + drop_rmap_locks(vma); } #define LATENCY_LIMIT (64 * PAGE_SIZE) @@ -193,15 +197,13 @@ unsigned long move_page_tables(struct vm if (pmd_trans_huge(*old_pmd)) { if (extent == HPAGE_PMD_SIZE) { bool moved; - VM_BUG_ON_VMA(vma->vm_file || !vma->anon_vma, - vma); /* See comment in move_ptes() */ if (need_rmap_locks) - anon_vma_lock_write(vma->anon_vma); + take_rmap_locks(vma); moved = move_huge_pmd(vma, old_addr, new_addr, old_end, old_pmd, new_pmd); if (need_rmap_locks) - anon_vma_unlock_write(vma->anon_vma); + drop_rmap_locks(vma); if (moved) { need_flush = true; continue; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org